Induction hardening is becoming increasingly popular in the manufacturing industry due to the controlled hardening offered by this technology. Improving the workpiece’s various physical, mechanical, and chemical properties is beneficial.

Understanding advantages and disadvantages of induction hardening helps to get the best result by minimizing possible defects and failures. This article will discuss all the advantages and disadvantages in depth.

How Does Induction Hardening Influence the Physical & Mechanical Properties?

The heating of the workpiece at a high temperature causes the austenite transformation, in which carbon atoms get trapped inside the crystal structure at the micro-level. The alternation of crystal structure leads to the strengthing of grain boundaries. As a result, the carbon atoms trapped inside the crystal structure increase the hardness, and the tight grain boundaries enhance the mechanical strength.

Let’s examine the other hardening approaches to demonstrate that induction hardening is superior.

Other Hardening Methods

Several different methods can be used to harden metals. Let’s discuss three major hardening approaches besides induction hardening, flame, furnace, and vacuum hardening.

  • Furnace hardening

The Furnace hardening process involves heating of workpiece into a heat treatment furnace in a controlled environment. The workpiece is heated until austenite transforms, after which a quick quenching occurs.

The furnace hardening cannot heat the workpiece as uniformly as induction hardening does. It heats all workpiece portions, while induction hardening can heat specific workpiece sections. Induction is a go-to option if you need to harden a particular portion.

  • Vacuum hardening

Vacuum hardening involves heating the workpiece by controlling the partial pressure, followed by a quick cooling process. It is often used for high-precision parts, as it can produce tough and consistent surfaces with minimal distortion.

Like the furnace hardening, it is also incapable of heating the workpiece at a specific region. The vacuum prevents the workpiece from reacting with atmospheric gases in the air, so the result is unaffected.

  • Flame hardening

Flame hardening also involves the hardening of the outer surface using a flame while maintaining the ductility of the core section. The depth capability of flame hardening ranges up to 10 mm. This process is typically used to harden small or thin parts or to harden specific areas of a more significant piece.

Since induction hardening does not use an open heating approach like flame hardening, it is more precise and does not create overheating, scaling, or decarburization damage.

What Are the Advantages of Induction Hardening?

Induction hardening offers a range of advantages over other hardening approaches. It is possible to harden a specific workpiece area with the exact penetration depth using induction hardening. Many applications require hardening the workpiece only on a particular section, which can be achieved by controlling the operational variables, such as the amount of current, heating time, and current frequency. In addition, a customized coil can be designed for the process based on specific use.

Following are the other key advantages of the induction hardening process.

  • Induction hardening can heat and cool a metal component much faster than other methods, such as flame or furnace hardening.
  • It customizes the hardness of the steel workpiece to the desired level.
  • Induction hardening is the best approach to get uniform hardening throughout the material structure.
  • It requires low manual labor and can be completely automated, depending on the requirements.
  • It is generally more energy efficient than other methods, as it heats and cools the component more quickly and requires less energy to maintain the high temperatures.
  • Induction hardening allows for greater control of the heating and cooling rates, which can result in a more consistent and precise hardening of the component.
  • The induction hardening process minimizes the risk of defective parts and directly contributes to the hardening cost. In addition, the automation in induction hardening reduces manual labor and helps to reduce the overall cost.

Click to see the different induction hardening methods.

Click to see how to do hardening and self-tempering.

What Are the Disadvantages of Induction Hardening?

The workpiece geometry and uniform heating are linked to the main drawbacks of induction hardening. If the workpiece geometry is intricate, the region close to the induction coil gets hotter than other sections. However, using the customized induction coil according to the shape of the workpiece eliminates the possibility of uneven heating.

Cracking in the workpiece is another possible disadvantage of induction hardening. Some of the few reasons include thermal expansion, thermal stress, and uneven quenching.

Following are the other key disadvantages of the induction hardening process.

  • The thermal expansion caused the concentration of impurities at grain boundaries, further leading to the weak grain structure resulting in intergranular cracking.
  • The rapid heating and cooling process in induction hardening can distort the hardened component. This can be a problem if the component requires precise dimensions or is prone to warping.
  • The cost might be a disadvantage if we compare the installation cost of induction hardening technology with other approaches, such as flame hardening and furnace hardening.
  • Induction hardening is not compatible with all types of metal and alloys. It is limited to specific grades of steel alloys. Low-carbon alloys like steel 8620, 1010, 12L14, and 1008 do not perform well under the induction hardening procedure.
  • The steel needs to have a certain level of carbon content (> 0.40%) to obtain a significant increment in hardening level.
  • It requires a high level of attention and expertise to ensure that the component is adequately heated and cooled to achieve the desired results.
  • Careful control of process parameters can be time-consuming and may require frequent monitoring and adjustments during the induction hardening process.

Summing Up

There is no doubt that induction hardening is one of the practical approaches to hardening steel alloys with a specific carbon content level. It offers uniform hardening, low-energy cost, quick lead time, and several other advantages.

It also has a few disadvantages, namely the possibility of cracking and high installation costs. However, Using FOCO’s sophisticated induction hardening machine makes the process cost-effective through its sustainability. Furthermore, the geometry of the workpiece and customizing the induction coil help prevent the risk of crack formation.